Human eyes, which are responsible for vision, are vital sensory organs that accept most information needed for life. The eye consists of the cornea and conjunctiva on the anterior surface, the iris and ciliary body in the sclera surrounding the eye, the lens, the vitreous body to maintain a spherical shape of the eye, and the posterior retina. The lens, vitreous body, and aqueous humor correspond to a refractive medium. Visual impairment or blindness of the eyes due to diseases is one of the biggest factors that reduce the quality of life.
Dry eye syndrome, which is also referred to as dry eye or keratoconjunctivitis sicca, is a disease associated with dryness of the ocular surface, i.e., the cornea and conjunctiva, due to a lack of tears or excessive evaporation of tears and is known as a disorder of the tear film. According to the International Dry Eye Workshop (DEWS) and the National Eye Institute (NEI) of the United States, dry eye syndrome refers to eye discomfort, tear film instability, and tear and eye surface diseases that cause vision loss. Dryness of the ocular surface affects damage to and inflammation of the corneal epithelium which is protected by the tear film. When the amount of the tear film is insufficient due to an increase in evaporation of the tear film or low secretion of tears from the lacrimal gland, an osmolarity of the tear film and friction of the ocular surface increase due to the lack of tears, thus causing inflammation due to damage to the corneal epithelium. Dry eye syndrome may be classified into aqueous tear-deficient dry eye syndrome and evaporative dry eye syndrome. The aqueous tear-deficient dry eye syndrome is caused by the lack of tears secreted in lacrimal gland. The evaporative dry eye syndrome is caused by excessive moisture loss from the ocular surface due to the lack of a viscous substance in tears occurring as a result of a reduced secretory ability of goblet cells of the conjunctiva and Meibomian gland of the eyelid although lacrimal gland secretion normally functions. These causes are divided into intrinsic causes due to intrinsic diseases that affect an eyelid structure or dynamics, and extrinsic causes leading to fast destruction of the tear film of the ocular surface due to partial external exposure.
Factors that cause dry eye syndrome are highly diverse, and non-limiting examples of such factors may include reduced tear secretion, excessive tear evaporation, inflammation of tear-producing organs, a case in which systemic diseases such as Sjogren's syndrome or Stevens Johnson syndrome are involved, a long-term use of smartphones, tablet PCs, or the like, and a rapid change in hormone.
Artificial tears and other treatments to reduce subjective symptoms, such as chondroitin sulfate, glutathione, hyaluronic acid, fibronectin, and serum eye drop are currently used to treat dry eye syndrome. But effects thereof have not yet been sufficient. Thus, the development of effective therapeutic agents for the treatment of dry eye syndrome has been required.
Meanwhile, imatinib is well known as Gleevec, which is a leukemia treatment drug, is a chronic myelogenous leukemia (CML) therapeutic agent, and was developed by Novartis. Imatinib selectively inhibits the activity of a tyrosine kinase produced by the Philadelphia gene (cancer genes created by the chromosomal translocation of Bcr and Abl genes), which is a major cause of CML. In addition, imatinib is also known to be effective in gastrointestinal stromal tumor (GIST) associated with stomach cancer in addition to CML. However, effects of imatinib on treating or preventing dry eye syndrome or dry eye syndrome-associated diseases have not yet been found.